The invention relates to the synthesis of inorganic hybrid nanoparticle structures using peptides which consist of two or more inorganic materials.
Bimetallic nanoparticles exhibit enhanced properties relative to single composition metal nanoparticles such as improvements in catalytic activity, changes in the plasmon energy band, and expected electronic gains. These properties are dependent upon nanoparticle size, structural organization, and composition of the bimetallic material. Therefore, approaches to their synthesis have involved the use of dendrimer hosts, reverse micelles, polyol processes, and microemulsions. For example, PdPt nanoparticles have been prepared within hydroxyl containing dendrimers by the addition of stoichiometric amounts of Pd4+ and Pt2+; while Au—Pd and Au—Pt bimetallic particles were synthesized with reverse micelles and polyvinylpyrrolidone, respectively. Unfortunately, these approaches offer little control with regard to the structural arrangement of each metallic component; and as a result, translate into poorly defined structures. Fundamentally, this is due to a lack of template specificity in arranging multiple metals in a fixed spatial orientation, i.e., templates containing single functionalities (OH or NH2) which bind many different metals (Pd, Ag, Au, Pt). For instance, hydroxyl containing dendrimers contain one functional group and a relatively large confined reaction space for synthesis, but are extended for the synthesis of two different metals with similar affinities in this confined area. Consequently, there is no discretion as to how metals are organized with respect to another to form the bimetallic material which ultimately affects the final physical properties of the hybrid material to the extent of not being fully exploited.
Alternatively, peptides designed with multi-functionality expand nanoparticle synthesis beyond single composition metal nanoparticles making it possible to controllably synthesize mixed compositions of inorganic nanoparticles in defined structures as outlined below.